When is petrol cheapest? Best day, time and where to fill up
Published on 2026-06-08
Fuel prices aren't fixed — they shift with the day of the week, demand and where you fill up. Knowing the patterns is the easiest way to pay less without changing your car or your habits.
Which day of the week?
People often say prices dip early in the week. In Refil's data for the last few weeks (October 2026) the weekday effect is small: well under 1% separates the cheapest and the priciest day. Prices do creep up before bank holidays and school breaks, when demand peaks.
What matters far more is where you fill up: the gap between two forecourts in the same town often beats 10-15p per litre, much bigger than any day-of-week swing.
Supermarkets vs motorway services
Supermarket forecourts (Tesco, Asda, Sainsbury's, Morrisons) are usually among the cheapest, while motorway services are reliably the most expensive — often 15-20p/L more. Avoid filling up on the motorway unless you're running on fumes.
Time of day
Filling early when fuel is cooler and denser gives a tiny theoretical edge, but it's negligible. Don't build your routine around it — picking the right station matters far more.
The easy way to always get it right
Instead of memorising rules, see the cheapest station near you at a glance with up-to-date prices. Refil highlights the cheapest option for your fuel on the map and flags the best day to fill up in your area.
FAQ
Is petrol really cheaper on a Monday?
Not by enough to plan around: in Refil's data the day of the week moves UK prices by well under 1%, far less than the gap between forecourts near you. Choosing the right station matters more.
How much can I save by choosing where to fill up?
The gap between forecourts in the same town can top 10-15p/L. On a 50-litre fill that's £5-£8 — hundreds of pounds a year.
Always find the cheapest option
Refil shows the cheapest petrol station or EV charger near you on the map, with official UK fuel prices. Download it free on the App Store.
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